German Amateur Radio Operator Bastian Blössl DF1BBL was working on a traffic light project when he stumbled across an idea to use his amateur radio skills to solve an RF dilemma.

As part of the project, Blössl needed to send an RF signal when traffic lights changed. He trialed a Baofeng radio, a popular and inexpensive amateur radio handheld device, usually found for less than $30.

The solution used a custom designed UDP packet to an audio flow graph in GNU Radio. GNU Radio then feeds the Baofeng. The radio’s built-in VOX function handles transmit switching.